End closure for explosive cartridges



June 27, 1944. c.'R.' JOHNSON ETAL END CLOSURE FOR EXPLOSIVE CARTRIDGESOriginal Fild March 9, 1959 2 Sheets-Sheet 2 7 INVENTORS C/var/es 5.15/0 Patented June 27, 1944 U NITED STATES i TENT OFFICE END CLOSURE FOREXPLOSIVE CARTRIDGES corporation of Delaware Original application March9, 1939, Serial No. 260,694. Divided and this application January 21941, Serial No. 372,742

4 Claims.

The present invention relates to a new and improved end closure forexplosive cartridges and to a method and apparatus for producing thesame.

This application is a division of U. S. application Serial No. 260,694,filed March 9, 1939, now Patent Number 2,326,310, dated August 10, 1943.

The various types of end closures for dynamite cartridges and the like,known heretofore, have been characterized by numerous imperfections anddisadvantages. No closure has been found to be satisfactory for alltypes of blasting explosives. In particular, conventional end closureshave been found to .be unsuitable for certain low density explosivecompositions. Difiiculty has been met in handling the loaded shells,because of the tendency of the loaded shell to spring open, permittingingress of water and often occasioning a loss of some of the explosivecharge.

The object of the present invention is the production of an improvedshell closure by a facile method. Another object is a method andapparatus which permit eificient formation of a closure of increasedmechanical strength. A further object is a device adapted to produceimproved interlocking folds in the shell material. Additional objectswill be disclosed as our invention is disclosed more fully hereinafter.

The foregoing objects are accomplished by the use of apparatus of noveldesign to produce an improved closure of depressed interlocking folds,in accordance with the method herein described. In order that theinvention may be understood more clearly, reference is made to theaccompanying drawings which illustrate a specific embodiment of ourinvention without limiting the scope thereof.

Referring generally to the various figures, Figure 1 is a plan Viewpartly in perspective and partly in cross-section of a member adapted torestrict the shell wall and to form folds at spaced intervals therein.Figures 2 and 3 are vertical views in cross-section on the lines 3-3 and2-2, respectively, of Figure 1. A vertical View in perspective of atamping means adapted for use in conjunction with the folding member isshown in Figure 4, whereas Figure 5 is a plan view of the top ofsaidtamping means. A preferred embodiment showing the tamping member inposition is illustrated in Figure 6. an end View of the closure. Figure8 is a sectional View of the improved crimp or closure produced on theend of the shell. Figure 9 is a view of the device in operation on adynamite shell.

Figure 10 is an enlarged side view in cross- Figure 7 is section of thebase of the sleeve of the tamping member, while Figure 11 is a plan viewof the base of said sleeve.

Similar numerals refer to similar parts throughout the several views.

Referring more specifically to Figure 1, which is a cross-sectional viewfrom the side of the folder member 8 which first engages the dynamiteshell, and to Figures 2 and 3, which are vertical views in cross-section0n the lines 33 and 22, respectively, of Figure 1, the numeral denotesthe circumeference on which lie the outermost points of the workingsurface. Said folder device may be constructed of wood, syntheticresins, non-sparking metal, and the like. The surface 3 between saidcircumference and the curved lines 2 is fiat or even and does not enterinto the operation of folding the shell. Starting with the curved lines2, the surfaces 4 slope downward and inward in the manner of the innersurface of a cone, viewed from its base toward the tip. The angle ofinclination in the present embodiment is 45 with respect to thehorizontal axis, and may be observed more readily by referring toFigures '2 and 3. The conical surfaces 4 extend to 5 the perimeter ofthe cylindrical portion of the folding device, said portion beingdesignated by the numeral 6. Rather deep grooves I extend diagonallydown through both the conical and cylindrical surfaces, in a mannersomewhat similar to a spiral, said grooves being characterized by onewall which rises in a substantially vertical plane with respect to thesurfaces 4, said wall being shown by the numeral 9 in Figures 2 and 3.

The method of operations is as follows: A cartridge 2| loaded with adynamic composition, but having one end open, is brought into contactwith a folding member 8 of proper size. The circumference of thedynamite shell in such case is approximately intermediate in sizebetween the circumference I of the cone, and the circumference 5 of thecylinder. Due to the fact that the surfaces 4 are in different planes,the shell wall contacts the aforementioned vertical walls 9 of thegrooves 1 at a point inside the outer extremities of said grooves,without touching the remainder of the surfaces 4. Upon the applicationof further pressure, said vertical walls having a rather sharp edgecause the shell material to crease, whereas contact of the remainder ofthe surface of the shell with the remainder of surfaces 4, forces thetop of the resulting folds or pleats into the groove 1. In this mannerthe open end of the shell is-restricted to a crossthat of thejrod 10.

section corresponding to that of the cylinder 6, and is characterized bya number of folds corresponding to the number of grooves, said foldsinclining toward the center and lying at an angle of about45" withrespect to the longitudinal axis of the shell, so that a spiral effectis produced. Due to the aforementioned inclination, the uppermost tipsof the folder shell areclosely grouped. 1

At this stage of the operation, the tamping pin is brought into play.This member has a diameter slightly less than that of the cylindricalaperture 6, through which it is pressed onto the gathered folds, withsuflicient force to crimp said folds against the body of the explosivewithin the shell. A preferred embodiment of the tampend of a chargeddynamite shell. Thus, the open end 20 of the shell H isshown'folded'inwards' 7 toward the cylinder 6 by contact with thevarious elements of the folder device 8 which are illus-' trated bydotted lines in Figure 9 and are shown in detail in Figures 1, 2 and 3.The tampin-g pin is depicted as disposed within the cylinder 6 and ingpin is illustrated in Figures 4 and 5. The

construction shown therein involves a rod l acting within a sleeve ll,said sleeve being provided with slots I4, which permit the escapeofexcessive moisture-proofing agent, as paraffin, for

same.

The details of the base of the tamping memher are shown in Figures 10and 11. It will be noted'thattheflat surface It of the sleeve ll isquite small in cross-section, the remainder'of the sleevewall I! havinga receding surface which slopes. inward." This particular design is welladapted to prevent slippage of the folds of the cartridge duringthetamping operation.

During said operation said folds first engage the flat surface l6. Saidsurface 16 must be a flat surface; if it werea sharp edge it would tendto; out said folds. V quite small in cross-section; if it were large incross-section it would be apt to cause slippage of said folds. The foldsof the cartridge, which first engage thefiatsurface 16, are directedthereby against the receding surface I! and thence V against'the bo'ttomof the rod in, whereby a uni form, conical crirnp of interlocking foldsis had.

Inactual operation, a spring H3 or other suitable tension member isslipped over the top part of the tamping pin whichis then placed in afixed position by inserting thatportion 22 of the rod Hi having areduced cross-section into. a carrying member l8 having an apertureadapted to retain the same. Such arrangement is illustrated in Figure 6.The spring I9 then rests snugly between the sleeve H and the carryingmember l8, and exerts sufficient pressure to cause the base of thesleeve to extend beyond Thus'When'the tamping operatic-n commences, onlythe retaining base of r the sleeve engages the shell fold at first, the

sleeve then being forced upward against the tension of'the spring as thepressure increases, the

rod being contacted only after said spring, has

v material directly, or may be brought forward with a twisting motion byrotating the same Howevensaid flat surface is.

approaching the gathered folds, showing the sleeve I in advance of thepin I0.

. Figure 8 depicts the resulting crimp which is conical 'in shape,uniformin structure and comprises interlocking folds of shell materialso that springing open of the crimp is avoided. A is a round bead or"reversed fold in the paper side walls of the cartridge. B is ashar'pbend in the wrapper material. C is the point at which the raw edges ofthe fold meet. D isthe point at which the raw edges of the aterialdouble back on themselves. In producing said improved end closure Withdepressed interlocking folds, displaying increased'strength, thefollowing factors should be considered. The reverse bend A should be assharp as practicable; The smaller the radius at A, the greater is thetendency of the closure to stay in place. The folding pin shouldbeshaped to produce a sharp break'at B, 'ef-' fecting a line or beadapproximately concentric with the cartridge wall. The endof the foldingpin H) (as illustrated inFigure 9) should bulge to produce a depressionin the central portion of the fold at C, which extends'deeper into thepowder than at B, thus effecting a somewhat conical structure and addingstrength'to the fold.

Each'fold or flute of paper D should overlap the adjacent foldiE, and soon around, forming a regular figure aboutthe center. Preferably, theline of the fold determined generally by the points A, B, and D, shouldbe as near a radial 7 line as is practicable. for thepurpose ofaddingstructural strength. The degree with which this fold approaches a radialline is determined by the number of flutes or folds around the center 7and by the shape of the tool causing the fold to be formed. i I

The'apparatus described in thei'foreg'oing' is particularly Well adaptedto machines employed for loading simultaneously a plurality of dynamiteshells, because the folding members as well as the tamping pins may beprovided readily iii series in such. manner that they coincide with thespacing of the cartridges during'the loading operation. Hence, after theexplosive hasbeen charged into the shells, it is a" simple matter toengage the top of said shells with a memberpro vided with the foldingand tamping membersip the requisite position. :i

In operating in accordance with-cup invention, it' is not necessary-torestrict thegnooves inthe folding member to'fla' definitenumber becausethe number most advantageous for theoperation is influenced by variousfactors,- among which may be mentioned the-physical characteristics ofthe flexible shell'material and the physical properties of the explosivecharged into the shell." Nor need the grooves'be maintained ata definitedepth,' it being possible-to obtainsatisL factory results withvariations indepth; depending on the diameter of the shell, and 'thestiffness "and weight of the materiaL'Of which said: shell about itsaxis at the tim of contact with the V is constructed. These possiblevariations in design, however, can be determined by experiment.

Likewise, the extension of the shell Wall be yond the level of theexplosive charge depends on the size of the shell being closed. Forexample, where it is desirable to close a shell 1 /2 inches in diameter,we have found that a very satisfactory end closure may be obtained ifthe closures of similar class which were known heretofore, and hencepermits enclosure of the various dynamite compositions currentlymanufactured, without danger of loss of the explosive charge because ofaccidental opening of the shell.

Furthermore, the end closure produced by the method and apparatus of ourinvention offers the additional advantages that it displays an increasedwater resistance, and enhanced imperviousness to moisture over closuresof the art. In addition this closure lends itself more readily to thevarious water-proofing and moisture-proofing methods such as theoperations of end spraying, coating or dipping with water-proofing orsealing compositions.

As is evident to those skilled in the art, our invention permits ofvarious modifications without departing from the spirit or scopethereof. We intend therefore to be limited only in accordance with thefollowing claims:

We claim:

1. In an apparatus for enclosing an explosive charge within a flexiblewrapper, the combination comprising a folding member and a tampingmember, said folding member being provided with an inner surfacesubstantially the shape of a truncated cone, and having a predeterminednumber of grooves extending upward from the base in spiral fashion toform interlocking folds in said wrapper upon being compressed thereon,said tamping member including a sleeve and a tamping pin movable withinsaid sleeve, said sleeve being adapted to being advanced and twistedagainst said folds followed by said pin to compress said folds againstthe explosive charge while maintaining said folds in interlockingrelationship.

2. In an apparatus for enclosing an explosive charge within a flexiblewrapper, the combination comprising a folding member and a tampingmember, said folding member being provided with an inner surfacesubstantially the shape of a truncated cone, and having a predeterminednumber of grooves extending upward from the base in spiral fashion toform interlocking folds in said wrapper upon being compressed thereon,said tamping member including a sleeve and a tamping pin movable withinsaid sleeve, at least a portion of the wall of which has a recedingsurface which slopes' inward, adapted to being advanced and twistedagainst said folds followed by said pin to compress said folds againstthe explosive charge while maintaining said folds in interlockingrelationship.

3. In an apparatus for enclosing an explosive charge within a flexiblewrapper, a folding mem her having an inner surface substantially theshape of a truncated cone provided with a predetermined number ofgrooves extending upward from the base in spiral fashion to forminterlocking folds in said wrapper upon being compressed thereon.

4. A method of enclosing a substantially cylindrical explosive charge ina flexible wrapper, which comprises simultaneously exerting downward andinward pressures on the overhanging cylindrical portion of the wrapperalong lines inclined with respect to the axis of the wrapper, therebystarting a formation of folds in said wrapper, continuing said pressureover the entire edge of the charge while causing all of the resultingfolds to incline at an angle from the longitudinal axis of said chargeand to incline at an angle from lines radial from the longitudinal axisof said charge, and compressing said folds against the end of saidexplosive charge while maintaining said folds in interlockingrelationship.

CHARLES R. JOHNSON. WILLIAM S. PILCI-IER. CHARLES B. STANLEY,

said sleeve being

